Process for spinning together a metal and a ceramic article



Nov. 21, 1939. a. J. MEYERS, JR

PROCESS FOR SPINNING TOGETHER A METAL AND A CERAMIC ARTICLE Filed Aug.24, 1937 Inventor: George J. MegePs-Jn,

His Attorneg.

Patented Nov. 21, 1939 UNITED STATES George J. Meyers, Jn, Lynn, Massassignor to General Electric Company, a corporation of New YorkApplication August 24, 1937, Serial No. 160,639

3 Claims.

My invention relates to a process for spinning together metal andceramic articles, and more particularly to a process for spinningaluminum reflectors on to glass globes of street lighting luminaires.

In the manufacture of street fighting luminaires, it is necessary toprovide a tight joint between the metal reflector and the glass globewhich encloses the open end thereof. The reflectors are generally madeof a comparatively soft metal, such as aluminum, and the globes are madeof a glass which may, or may not, be prismatic. The line of contactbetween these two members is circular, and is anywhere from 8 to 18inches in diameter. The spinning of: these large units under ordinarycircumstances and methods has resulted in a costly breakage of globeswhich made it impractical to unite the reflector and globe in thisdesirable manner.

I have discovered that this disadvantage is overcome by heating thereflectors up to a certain temperature range before spinning them on tothe glass globes. By including this step in the process, a satisfactorydustproof and waterproof joint is obtained with only a small breakage ofthe glass globes which is substantially negligible.

One object of my invention is to provide a process whereby the breakageof glass globes during the spinning process is substantially ellminated.

For a better understanding of my invention, together with other andfurther objects thereof, reference is had to the following description,taken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

In the accompanying drawing, Fig. l illustrates a heating device forreflectors used in the manufacture of street lighting luminaires; Fig. 2illustrates, partly in section, the assembled reflector and globesupported in a lathe ready for spinning the two together; and Fig. 3illustrates an enlarged fragmentary cross-sectional view of thecompleted joint between the reflector and globe.

Referring to the drawing in detail, Fig. 1 discloses a sectional frontelevation of a heater 5 which is a sheet metal cylinder open at the topand closed at its bottom by a heating unit 6. This heating unit ispreferably an electric resistance unit supplied with current through thelead "I. The upper end of the heater is provided with supporting ears 8bent inwardly to engage the edge of a metal reflector 9. This reflectoris provided with a flange l0 and deflectors II, which project below theedge of the flange into the heater. The diameter of the flange I0 issuch that it substantially closes the upper end of the heater 5, wherebypractically all of the heat rising from the heater 6 is absorbed by thereflector. The reflector 9 is in the form of a conoid open at both ends,the upper end being provided with a flange l2, by means of which it issupported, and through which opening the lamp projects into thereflector, and is made of aluminum which is treated in accordance with aprocess known under the trade name Alzak. This process provides thealuminum with a hard specular surface having high reflectivity.

The reflector is heated to a temperature of the order of 88? C. whichhas been found to be. most suitable for this purpose. The reflector isthen assembled with a globe l3, and is supported between the head stockI l and the tail stock l5 of a lathe by means of cupped supportingmembers l6 and 11. This step in the process is performed quickly so thatthe reflector temperature is not substantially reduced before thespinning operation. The assembled unit is then slowly turned and theflange ID of the reflector is slowly, crimped, or spun, to conform tothe surface of ridges near the edge of the globe 83, by means of a tooll8 resting on a tool rest l9.

In Fig. 3, I have illustrated an enlarged sectional view of the jointformed, as above described, between the reflector 9 and the globe H3.The globe i3 is provided with a pair of parallel ridges 20 and 2!between which a groove 22 is formed. The flange I0 is first slowlyformed around the first ridge 2|], then slowly turned into the groove22, and finally the end thereof is formed about the second ridge 2 I. Inthis manner, a wide contact surface is obtained between the reflectormetal and the surface of the glass globe l3.

The process, as above described, has substantially eliminated glassbreakage during the spinning process, and has made practicable thespinning together of aluminum reflectors and globes of luminaires inlarge quantities. I am not certain at present of the exact theory uponwhich the success of my'above-described process rests, but I believe itto be due to the high coeflicient of expansion of aluminum. When theflange of the reflector is cold spun on to the glass globe, considerablepressure must be exerted by the operator in an attempt to obtain a jointwhich is sufilciently tight to prevent water getting into the luminaire.Furthermore, due to the resiliency of the metal, the metal springs awayfrom the glass flange and it is almost impossible to get awatertight fltbetween the metal and the glass. In attempting to make such jointsufliciently tight to pass inspection,,the operator exerts a greaterpressure than is permissible, with the result of excessive breakage ofglobes.

By preheating the reflector, as above described, the reflector isexpanded, and simultaneously, the oxide coating in the aluminum issoftened so that the aluminum becomes more pliable and responds to thetool of the operator more readily than when it is cold. As a resultthereof, the force required to spin the metal into the ridges to formthe joint is minimized, and after the reflector is cooled to thetemperature of the globe, the metal contracts and the joint becomestighter than was possible to obtain with the cold spinning of thereflector.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The process of spinning an aluminum reflector on to a glass globewhich comprises heating said reflector to substantially expand saidreflector without injuring its reflecting surface, assembling saidreflector and globe, and turning the assembled unit while spinning theflange of the reflector over a cooperating flange on the glass globe.

2. A process of joining an aluminum reflector and a glass globe to forma dust tight unit comprising heating the reflector to -a temperature ofthe order of 88 C., and thereafter spinning the edge of said reflectorover a cooperating flange on the edge of the globe.

3. The process of spinning an aluminum reflector on to a glass globewhich comprises heating said reflector to a temperature of the order of88 C., and thereafter spinning the edge thereof over the edge of a glassglobe before the reflector has had time to cool.

GEORGE J. MEYERS, JR.

